Now thats really cool. Figured the Z rated stuff was way better than 200
MPH, but had no idea it would go 400+ MPH.
JB, #79
----- Original Message -----
From: "Rex Svoboda" <svoboda@marsweb.com>
To: "land-speed-digest" <land-speed@autox.team.net>
Sent: Wednesday, July 02, 2003 1:21 PM
Subject: tire test
> List:
> Here are spin test results on the tire I use on my car. The test
> was done to gather safety information not otherwise available on this
> tire. These results are for information and entertainment only, etc.
> Many thanks to Gene and Betty Burkland (and Betty's brothers) for taking
> the time and effort to do the test.
>
>
> Tire: New, off the shelf, Michelin Pilot Sport 275/40 ZR 17
> unshaved.
> tire air pressure- 50 psi
> mounted tire out of round- .006"
> start circumference- 80.6875"
> air temp. 70' F
>
> test- tire held at noted RPM's for 20 seconds, then stopped and
> measured. free (unloaded) spin
>
> Spin # 1: 2,000 tire rpm radius growth 1/8" 155
> mph
> 2,500 tire rpm radius growth
> 1/4" 196 mph
> 3,500 tire rpm radius growth
> 5/16" 275 mph
> circumference at rest- 81"
> tire psi after run- 50 psi
>
> Spin # 2: 4,000 tire rpm radius growth 1/2" 319 mph
>
> 4,500 tire rpm radius growth 1/2" + 359
> mph
> circumference at rest- 81.250
> tire psi after run- 50 psi
>
> Spin # 3: 5,000 tire rpm radius growth 5/8" 403
> mph (spinner operators were backing up at this point)
> 5,172 tire rpm tire
> failure 417 mph
>
> Notes: no shake or vibration during the test. The bead was stable on
> the wheel until 200 rpm prior to failure.
> parts of the tire flew 500' from the spinner which was
> pretty cool to watch & we were hunting tire pieces for 30
> minutes in the wheat field.
> Using a 68% safety factor there is still a large margin
> when running the car at 200 mph.
>
> Rex Svoboda
> 631 G/MS
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